Just to share my view.
1) Checking sustain
Pick the G string and try to feel the vibration on the guitar body and neck.
On Ibanez I can't feel it that much, neither did Les Paul. But on a Strat I can totally feel it; and with different wood, the effect is slightly different.
With a good amp, this kind of sustain can also be heard over the amp.
2) Checking Neck
Press down 1st and the last fret, see that the gap from string on 8th fret is about 1/4 mm. Then check action at 17th fret should be about 2.4mm Then check string buzz. About the shape I'm used to V-shaped, up to individual. Then the fingerboard has various diameter, 9.5" is in the middle. Fast player might prefer 12" and have a lower action.
3) Pickup
Check the pickup, and see whether balanced. gap from pole to string should be 2.4mm - 3.6mm
4) Machines
Locking tuner? LSR nut? 5 springs still attached? set screw to adjust the bridge height still OK or worn out?
1) Checking sustain
Pick the G string and try to feel the vibration on the guitar body and neck.
On Ibanez I can't feel it that much, neither did Les Paul. But on a Strat I can totally feel it; and with different wood, the effect is slightly different.
With a good amp, this kind of sustain can also be heard over the amp.
2) Checking Neck
Press down 1st and the last fret, see that the gap from string on 8th fret is about 1/4 mm. Then check action at 17th fret should be about 2.4mm Then check string buzz. About the shape I'm used to V-shaped, up to individual. Then the fingerboard has various diameter, 9.5" is in the middle. Fast player might prefer 12" and have a lower action.
3) Pickup
Check the pickup, and see whether balanced. gap from pole to string should be 2.4mm - 3.6mm
4) Machines
Locking tuner? LSR nut? 5 springs still attached? set screw to adjust the bridge height still OK or worn out?